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a) \(\frac{x+2}{-5}=\frac{2}{15}\)
=> \(\left(x+2\right).15=\left(-5\right).2=-10\)
=> \(x+1=\frac{-10}{15}=-\frac{2}{3}\)
=> \(x=-\frac{2}{3}-1=-\frac{5}{3}\)
b) \(\frac{x-1}{3}=\frac{2x+5}{5}\)
=> \(\left(x-1\right).5=\left(2x+5\right).3\)
=> \(5x-5=6x+15\)
=> \(-15-5=6x-5x\)
=> \(x=-20\)
c) \(\frac{-3}{3x-2}=\frac{4}{2x+1}\)
=> \(-3.\left(2x+1\right)=4.\left(3x-2\right)\)
=> \(-6x+\left(-3\right)=12x-8\)
=> \(-18x=-5\)
=> \(x=\frac{5}{18}\)
7 người bạn có số cái bắt tay là :
7 x 6 : 2 = 21 ( cái )
6 người kia đã bắt tay số bạn là :
1 + 2 + 3 + 4 + 5 + 6 = 21 ( bạn )
Bạn G bắt tay số bạn là :
21 - 21 = 0 ( bạn )
Đáp số : 0 bạn
a, ta có:27:3,6=7,5
=>-2x7,5=15
vậy x cần tìm là 15
b, -0,52:x=\(-\frac{4}{7}\)
\(\frac{-13}{25}\): x=\(\frac{-4}{7}\)
x=\(\frac{-13}{25}:\frac{-4}{7}\)
x=0,91
\(a,3,8:2x=\frac{1}{4}:2\frac{2}{3}\)
\(\Leftrightarrow3,8:2x=\frac{3}{32}\)
\(\Leftrightarrow2x=3,8:\frac{3}{32}\)
\(\Leftrightarrow2x=\frac{608}{15}\)
\(\Leftrightarrow x=\frac{304}{15}\)
\(b,0,25x:3=\frac{5}{6}:0,125\)
\(\Leftrightarrow0,25x:3=\frac{20}{3}\)
\(\Leftrightarrow0,25x=20\)
\(\Leftrightarrow x=80\)
\(c,0,01:2,5=0,75x:0,75\)
\(\Leftrightarrow0,75x:0,75=\frac{1}{250}\)
\(\Leftrightarrow x=\frac{1}{250}\)
Mik lm hơi tắt chỗ nào chw hiểu thì hỏi mik nhé
a) - 0,52 : x = - 9,36 : 16,38
- 0,52 : x = \(-\frac{4}{7}\)
\(x=\left(-0,52\right):\left(-\frac{4}{7}\right)=\frac{91}{100}=0,91\)
b) \(\frac{4\frac{1}{4}}{2\frac{7}{8}}=\frac{x}{1,61}\)
\(\frac{\frac{17}{4}}{\frac{23}{8}}=\frac{x}{1,61}\)
\(\frac{x}{1,61}=\frac{34}{23}\)
\(x=\frac{34}{23}.1,61=2,38\)
1) a) Ta có: \(\frac{x}{-15}=\frac{-60}{x}\) \(\Rightarrow x^2=\left(-15\right).\left(-60\right)=900\)
\(\Rightarrow x=30\)
b) \(\frac{-2}{x}=\frac{-x}{\frac{8}{25}}\) \(\Rightarrow x.\left(-x\right)=\left(-2\right).\frac{8}{25}\)
\(\Rightarrow x.\left(-x\right)=\frac{-16}{25}\)
\(\Rightarrow x.\left(-x\right)=\left(\frac{-4}{5}\right).\frac{4}{5}\)
Vậy \(x=\frac{4}{5}\)
2) a) \(3,8: \left(2x\right)=\frac{1}{4}:2\frac{2}{3}\)
\(\Rightarrow3,8: \left(2x\right)=\frac{3}{32}\)
\(\Rightarrow2x=\frac{3}{32}:3,8=\frac{15}{608}\)
\(x=\frac{15}{608}:2=\frac{15}{1216}\)
Vậy \(x=\frac{15}{1216}\)
b) \(\left(0,25x\right):3=\frac{5}{6}:0,125\)
\(\Rightarrow\left(0,25x\right):3=\frac{20}{3}\)
\(\Rightarrow0,25x=\frac{20}{3}.3=20\)
\(\Rightarrow x=20:0,25=80\)
Vậy x = 80
c) \(0,01:2,5=\left(0,75x\right):0,75\)
\(\Rightarrow\frac{1}{250}=\left(0,75x\right):0,75\)
\(\Leftrightarrow0,75x=\frac{1}{250}.0,75=\frac{3}{1000}\)
\(\Rightarrow x=\frac{3}{1000}:0,75=\frac{1}{250}\)
Vậy \(x=\frac{1}{250}\)
d) \(1\frac{1}{3}:0,8=\frac{2}{3}:\left(0,1x\right)\)
\(\Rightarrow\frac{5}{3}=\frac{2}{3}:\left(0,1x\right)\)
\(\Rightarrow0,1x=\frac{5}{3}.\frac{2}{3}=\frac{10}{9}\)
\(\Rightarrow x=\frac{10}{9}:0,1=\frac{100}{9}\)
Vậy \(x=\frac{100}{9}\)
a) \(\frac{x}{-15}=\frac{-60}{x}\Leftrightarrow x.x=-15.\left(-60\right)\Leftrightarrow x^2=900\Leftrightarrow x^2=\orbr{\begin{cases}30^2\\\left(-30\right)^2\end{cases}}\Leftrightarrow x=\orbr{\begin{cases}30\\-30\end{cases}}\)
a)\(\frac{x}{27}=\frac{-2}{3,6}\)
=>x.3,6=27.(-2)
=>x.3,6=-54
=>x=-15
b)-0,52:x=-9,36:16,38
=>-0,52:x=-4/7
=>x=0,91
c)\(\frac{4\frac{1}{4}}{2\frac{7}{8}}=\frac{x}{1,61}\)
=>\(2\frac{7}{8}.x=4\frac{1}{4}.1,61\)
=>\(2\frac{7}{8}.x=\frac{2737}{400}\)
=>x=\(\frac{119}{50}\)
a,\(\frac{x}{27}=-\frac{2}{3,6}\)
\(\Leftrightarrow x.3,6=27.-2\)
\(\Leftrightarrow x.3,6=-54\)
\(\Leftrightarrow x=-15\)
b,\(-0,52\div x=-9,36\div16,38\)
\(\Leftrightarrow-0,52\div x=-\frac{4}{7}\)
\(\Leftrightarrow x=\frac{91}{100}\)
c,\(\frac{4\frac{1}{4}}{2\frac{7}{8}}=\frac{x}{1,61}\)
\(\Leftrightarrow\frac{4,25}{2,875}=\frac{x}{1,61}\)
\(\Leftrightarrow x.2,875=4,25.1,61\)
\(\Leftrightarrow x.2,875=6,8425\)
\(\Leftrightarrow x=2,38\)
\(a,-0,52:x=-9,36:16,38\)
\(\Leftrightarrow\frac{-13}{25}:x=\frac{-4}{7}\)
\(\Leftrightarrow x=\frac{-13}{25}:\frac{-4}{7}\)
\(\Leftrightarrow x=\frac{91}{100}\)
\(b,\frac{x}{-15}=\frac{-60}{x}\)
\(\Leftrightarrow x^2=900\)
\(\Leftrightarrow x^2=\left(30,-30\right)^2\)
\(\Leftrightarrow\orbr{\begin{cases}x=30\\x=-30\end{cases}}\)
\(c,\frac{-2}{x}=\frac{-x}{8}\)
\(\Leftrightarrow-\left(x^2\right)=-16\)
\(\Leftrightarrow x^2=16\)
\(\Leftrightarrow x^2=\left(4,-4\right)^2\)
\(\Leftrightarrow\orbr{\begin{cases}x=-4\\x=4\end{cases}}\)
\(d.3,8\div2x=\frac{1}{4}:2\frac{2}{3}\)
\(\Leftrightarrow3,8\div2x=\frac{3}{32}\)
\(\Leftrightarrow2x=3,8\div\frac{3}{32}\)
\(\Leftrightarrow2x=\frac{608}{15}\)
\(\Leftrightarrow x=\frac{608}{15}\div2\)
\(\Leftrightarrow x=\frac{304}{15}\)
\(e.0,25x\div3=\frac{5}{6}:0,125\)
\(\Leftrightarrow0,25x\div3=\frac{20}{3}\)
\(\Leftrightarrow0,25x=\frac{20}{3}.3\)
\(\Leftrightarrow\frac{1}{4}x=20\)
\(\Leftrightarrow x=20:\frac{1}{4}\)
\(\Leftrightarrow x=80\)